b'DRYER SECTION INNOVATIONSaddition, achieve clearly improved runnability because (amongst other things) the number of sheet breaks was reduced. The same applied to the second part of the dryer section restructuring (fourth group). When calculating additional turnover referred to above, it should in theory be possible to add considerably to the top line. However, this is not always quite so straightforward;Figure 4. Recommended air flow from the pockets.calculations of economic efficiency vary considerably in practice. The best way to approach this, GeorgiMOISTURE: A MOST IMPORTANT DETAIL pockets are ventilated, the absolute makes clear, is to look at everyA customer asked to measure andmoisture is lowered by 38% - a machine for what it is: unique. And,evaluate the status of his pocketsignificant reduction. Conversely, naturally, if every paper machine isventilation. Fig. 5 shows the TASK logthe pockets that are not ventilated different, the numbers will always beincluding all relevant parameters.Blowcontain much more moisture. In relative. Nevertheless, an increaseboxes were installed on this paperconclusion, the blow boxes made it in economic efficiency of 17% is anmachine only in the pockets underpossible to absorb significantly more impressive argument on its own.cylinders 30, 33, 36, and 38.water that was transported away in these pockets. This importance USING BLOW BOXES This gave an uneven result in termsis obvious when comparing Fig. 5As a general principle, it is fair toof ventilation. In places where thewith a different machine configuration.say that Slalom groups and optimal pocket ventilation are almost always beneficial. Blow pipes are not always necessarily needed, as other techniques can be effective. Slalom groups blow boxes, for example, are a sensible alternative: these, like blow pipes, are placed behind the doctor, so that air in the pockets is distributed evenlyfrom the middle of the machine to both the front and the drive side (Fig. 4). An accumulation of moisture towards the machine centre is therefore avoided; the sheet is also better pressed to the dryer fabrics.an increase And a stabilised sheet significantlyin economic and effectively reduces possible sheetefficiency of fluttering. Optimal pocket ventilation:17% is an many practical benefits, one source. Aimpressive further example demonstrates why argument on as so oftenuniformity is crucial. Figure 5. Uneven pocket ventilation = uneven moisture removal. its own36 WORLD PULP&PAPER'